Sea Technology

DEC 2012

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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pieces of marine debris from one pier in Boston Harbor. In addition, there were 220 participants who helped topside with tether handling and down below as spotters and ROV co-pilots. Detecting Derelict Fishing Gear Rozalia Project was contracted in August 2011 by the Blue Ocean Society for Marine Conservation to perform a survey of derelict fshing gear along the New Hampshire coast. The objective was to begin a quantity and distribution study of derelict lobster traps Derelict lobster traps on the seafoor in Gosport Harbor, Isles of Shoals. The with the aim of returning for future trap reimage was taken by a VideoRay Pro 4. (Photo Credit: Rozalia Project for a moval. Clean Ocean) The initial piece of equipment we used was the Tritech Starfsh side scan sonar. eoRay images revealed areas of the seafoor with derelict Twenty-eight miles of ocean were surveyed towing the Startraps strewn around or lying on top of one another. Thanks fsh behind the Rozalia Project vessel American Promise in to the Smart Tether, the team knew the location of the ROV primarily protected waters 30 to 115 feet deep, with 0 to 15 and could cross-reference the VideoRay images with those knots of wind and up to 2-foot waves. from the sonar to train others to differentiate between potenInitially, the biggest challenge was learning to interpret tial derelict traps and rocks. the side scan sonar images. The team found instances where Once team members learned how to read the sonar imthe bottom was covered in blocks of granite, rather than ages, they ran 15-minute transects with the Starfsh. The sand. These granite rocks had a similar look to the rectanguteam recorded the side scan log fle and took screenshots lar derelict traps. each time an area of interest with potential derelict traps apIn order to clarify the images, the VideoRay ROV and peared. Local lobstermen advised that traps in a "V" or "W" BlueView multibeam sonar were used to get two additional formation would likely be derelict because they are set in views of the rocky areas. By doing so, the team obtained a line and storms or boats—both signifcant contributors to close-in sonar images and video images of areas that were, the problem of derelict gear—could disrupt that line. Traps in fact, boulders covered in organic matter. Subsequent Vidin this area were most often set in lines of three, so if one or two traps were spotted in a location, they were counted as potential derelict traps. In addition, the team counted areas of traps on the bottom without any surface buoys in the vicinity as potential derelict traps. At the conclusion of the study, Rozalia Project had identifed 1,570 potential derelict traps over 28 miles of ocean off the coast of New Hampshire and near the Isles of Shoals. Rozalia Project planned to begin trap removal in August, working with Blue Ocean Society. Using an ROV with a hook leading to a line on the surface, the team will hook the traps, then transfer the line to a boat. Conclusion and Future Work Since the start of 2011, Rozalia Project has picked up more than 133,675 pieces of marine debris with more than 5,000 participants in its programs. While the majority of that debris came from shorelines, much of it came off the seafoor without disturbing or disrupting fragile marine habitats. Rozalia Project has found that each piece of underwater technology it uses has signifcant strengths and limitations. Integrating the equipment allows the project to achieve its mission of locating and removing marine debris, from the surface to the seafoor, without any impact to the marine environment other than cleaning it up. n Rachael Miller is the co‐founder and executive director of Rozalia Project for a Clean Ocean. She has a background in marine studies and underwater archaeology, which she studied at Brown University. She is a trainer for VideoRay LLC and founder of Lake Champlain Shipwrecks, running the frst commercial, ROV‐supported shipwreck tours in the U.S. 60 st / DECEMBER 2012 www.sea-technology.com

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